Cleaning apparatus and cleaning method for wafer

ABSTRACT

A front surface of the wafer is contacted with a straight-shaped front surface cleaning brush, and a pressure is applied on the front surface cleaning brush from both ends to enlarge the diameters in both end portions of the front surface cleaning brush. The front surface cleaning brush rotates with a shaft being an axis. An inner surface of the front surface cleaning brush is directly in contact with a surface of the shaft. The front surface cleaning brush is composed of a single structure made of synthetic resin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 11/411,874,filed Apr. 27, 2006, (which issued as U.S. Pat. No. 7,908,698 on Mar.22, 2011) which claims priority of Japanese Patent Application No.2006-008323, filed on Jan. 17, 2006, the entire contents of which areincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cleaning apparatus and a cleaningmethod for a wafer preferable for manufacturing a semiconductor device.

2. Description of the Related Art

Recently, in a manufacturing process of a semiconductor device, it isbecoming essential to planarize a film or the like having been formed bythat time by performing a CMP (Chemical Mechanical Polishing) processingbefore a photolithography, in order to secure an exposure margin for thephotolithography. Here, a method of planarization by the CMP processingwill be described with reference to FIG. 10. FIG. 10 is a schematic viewshowing an outline of a CMP apparatus.

The CMP apparatus is provided with a polishing table 51 on a surface ofwhich a polishing pad 52 is affixed, a polishing head 54 holding a wafer53, and a slurry supplying nozzle 55 supplying slurry (suspensioncontaining a grain of abrasive) 56. Further, the CMP apparatus isprovided with a dressing apparatus 57 dressing the polishing pad 52. Thepolishing table 51 and the polishing pad 52 are rotatable around theirown axes.

In a CMP processing using the CMP apparatus with such a constitution,the slurry 56 is supplied from the slurry supplying nozzle 55 onto thepolishing pad 52 while the polishing table 51 is being rotated, and thewafer 53 is pressed on the polishing pad 52 while the polishing head 54is being rotated. As a consequence, the wafer 53 is polished by thepolishing pad 52. To a portion of the polishing pad 52 which is squasheddue to the wafer 53 being pressed on, a dressing is performed by thedressing apparatus 57 during rotation.

The CMP processing is performed as above, and the abrasive graincontained in the slurry, metal impurity, or the like remain on the wafer53 after the CMP processing. Thus, a cleaning of the wafer 53 isrequired after the CMP processing. Here, a conventional cleaning methodof a wafer will be described with reference to FIG. 11 and FIG. 12. FIG.11 is a perspective view showing a conventional cleaning apparatus,while FIG. 12 is a front view showing the conventional cleaningapparatus.

The conventional cleaning apparatus is provided with two cylindricalbrushes 63 contacting a front surface and a rear surface of the wafer53, respectively. The brush 63 is made of synthetic resin and aplurality of projections are formed on a surface thereof. Additionally,a shaft 62 is inserted into the brush 63. In a cleaning using thisapparatus, the brushes 63 and the wafer 53 are rotated while the twobrushes 63 are made to contact the front surface and the rear surface ofthe wafer 53.

It is also carried out that a plurality of such cleaning apparatuses areprovided to perform cleanings using different cleaning solutions. Forexample, after a cleaning is performed with an ammonia solution beingsupplied, another cleaning may be performed with a fluorinate acid beingsupplied. By this method, the abrasive grain is removed by the cleaningusing the ammonia solution and the metal impurity is removed by thecleaning using the fluorinated acid.

By these methods, a sufficient cleaning is possible for a wafer with adiameter of 200 mm or less. However, when the cleaning is performed fora wafer with a diameter of about 300 mm according to the above-describedmethod, numerous foreign objects 58 remain on an outer peripheralportion of the wafer 53 as shown in FIG. 13. This is considered becausetimes during which a central portion and the peripheral portion of thewafer 53 contact the brush 63 are different. That is, in the peripheralportion, time during which the wafer is apart from the brush 63 isrelatively long and a cleaning efficiency is deteriorated.

Thus, there is disclosed an art in which a brush having larger diametersin both ends is used to increase the cleaning efficiency in the outerperipheral portion (Patent Document 1).

However, using the brush having the larger diameters in the both ends isnot practical. This is because a variation of the diameter of the brushmust be adjusted in response to the diameter of the wafer. Moreover,since a direction and an amount of a warp of the wafer vary in responseto a kind, a number, and a pattern and the like of films already formed,it is required to prepare more various brushes in order to correspondalso thereto.

For example, in such a case as after a CMP processing for forming anelement isolation region by STI (Shallow Trench Isolation), the wafer 53is warped into a shape of a mound as shown in FIG. 14A. As a result, onthe front surface of the wafer 53 the outer peripheral portion is hardto contact the brush 63. On the other hand, in such a case as after aCMP processing for forming a metal wiring, the wafer 53 warps into ashape of a bowl as shown in FIG. 14B. As a result, on the front surfaceof the wafer 53 the outer peripheral portion is easy to contact thebrush 63, while on the rear surface the outer peripheral portion is hardto contact the brush 63. Therefore, unless brushes of a plurality ofkinds are prepared for the same wafer, foreign objects on the frontsurface and the rear surface of the wafer 53 cannot be removedsufficiently. Additionally, not only the direction of the warp but alsothe amount of the warp varies in response to a film forming condition orthe like as described above.

As described above, in the conventional method in which the brush withthe varied diameter is used, it is required to prepare various brushes,resulting in a higher cost.

Though it is possible to remove the foreign objects using conventionalbrushes if the cleaning is performed for a long period of time, a timeperiod of at least about three to four times of a time period requiredfor the cleaning of the wafer with the diameter of about 200 mm isnecessary. As a result, a throughput is substantially decreased.

Related arts are disclosed in Patent Document 1 (Japanese PatentApplication Laid-open No. 2003-163196) and in Non-patent Document 1(Clean Technology VOL. 8, No. 5 (May 1998)).

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a cleaning apparatusand cleaning method for a wafer which are capable of reliably cleaningvarious wafers without using various kinds of brushes.

In order to solve the above problem, the present inventor has devisedembodiments of the present invention described below as a result ofacute study.

A cleaning apparatus for the wafer according to the present invention isprovided with a straight-shaped front surface cleaning brush contactinga front surface of the wafer, and a pressurizer enlarging diameters inboth end portions of the front surface cleaning brush by means ofapplying a pressure on the front surface cleaning brush from both ends.

In a cleaning method for the wafer according to the present invention, astraight-shaped front surface cleaning brush is made to contact asurface of the wafer, and diameters in both end portions of the frontsurface cleaning brush is enlarged by means of applying a pressure onthe front surface cleaning brush from both ends.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view showing a cleaning apparatus for a wafer accordingto a first embodiment of the present invention;

FIG. 1B is a front view showing the cleaning apparatus for a waferaccording to the first embodiment of the present invention;

FIG. 1C is a side view showing the cleaning apparatus for a waferaccording to the first embodiment of the present invention;

FIG. 2 is a view showing a brush 3;

FIG. 3 is a view showing a cleaning system for a wafer;

FIG. 4 is a view showing an operation of the first embodiment of thepresent invention;

FIG. 5 is a view showing a result of an observation (in a case in whicha pressurizing is performed) actually carried out;

FIG. 6 is a view showing a result of the observation (in a case in whichthe pressurizing is not performed) actually carried out;

FIG. 7 is a front view showing a cleaning apparatus for a waferaccording to a second embodiment of the present invention;

FIG. 8A is a view showing a shaft 12;

FIG. 8B is a view showing a cross section along a line I-I in FIG. 8Aand a stopper 11;

FIG. 9 is a view showing an operation of the second embodiment of thepresent invention;

FIG. 10 is a view showing a planarization method by a CMP processing;

FIG. 11 is a perspective view showing a conventional cleaning apparatus;

FIG. 12 is a front view showing the conventional cleaning apparatus;

FIG. 13 is a view showing a result of a cleaning using the conventionalcleaning apparatus;

FIG. 14A is a view showing a problem in a conventional cleaning method;and

FIG. 14B is a view showing a problem in the conventional cleaning methodas well.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be describedconcretely with reference to the attached drawings.

First Embodiment

To begin with, a first embodiment of the present invention will bedescribed. FIG. 1A is a top view showing a cleaning apparatus for awafer according to the first embodiment of the present invention. FIG.1B is a front view showing the cleaning apparatus for the waferaccording to the first embodiment of the present invention. FIG. 1C is aside view showing the cleaning apparatus for the wafer according to thefirst embodiment of the present invention.

In the first embodiment, there are provided a cylindrical front surfacecleaning brush 3 a and a cylindrical rear surface cleaning brush 3 bwhich contact a front surface and a rear surface of a wafer 21respectively, as shown in FIG. 1A to FIG. 1C. Hereinafter, the frontsurface cleaning brush 3 a and the rear surface cleaning brush 3 b maybe referred to generically as brushes 3. The brushes 3 are made ofsynthetic resin such as PVA (Poly Vinyl Alcohol), for example, onsurfaces of which a plurality of projections are formed as shown in FIG.2. A diameter of the projection is, for example, about 5 mm. Shafts 2are inserted to the brushes 3. Each brush 3 can be rotated with theshaft 2 being an axis. Additionally, rollers 4 rotating the wafer 21 areprovided. Further, there are disposed a pure water nozzle 5 a spraying apure water to the front surface of the wafer 21, a pure water nozzle 5 bspraying a pure water to the rear surface, a chemical nozzle 6 aspraying a chemical solution (cleaning agent) to the front surface, anda chemical nozzle 6 b spraying a chemical solution (cleaning agent) tothe rear surface. Incidentally, instead of using these nozzles, acommunication path for liquid may be provided inside the brush 3 so thatthe pure water and the chemical solution are supplied from inside thebrush 3.

Further, in the present embodiment, along a direction in which the shaft2 extends, there are provided pressure portions 1 which apply pressureson the brush 3 from both ends thereof. The pressure portion 1 isconstituted using a pressure mechanism by a diaphragm system, forexample. When the pressure portions 1 apply the pressures on the brush3, both side portions of the brush 3 are compressed and the diametersthereof become large in the both end portions.

In a cleaning system including the cleaning apparatus according to thefirst embodiment, as shown in FIG. 3 for example, there are provided afirst brush unit 11 and a second brush unit 12 which include thecleaning apparatuses respectively, and further, a cleaning/drying unit13 is provided in a subsequent step. In the first brush unit 11, acleaning agent of alkali or the like which is capable of removingabrasive grain is sprayed from the nozzles 5 a and 5 b. On the otherhand, in the second brush unit 12, a cleaning agent of acid or the likewhich is capable of removing metal impurity is sprayed from the nozzles5 a and 5 b. For example, an ammonia solution is sprayed from thenozzles 5 a and 5 b of the first brush unit 11, while a hydrofluoricacid is sprayed from the nozzles 5 a and 5 b of the second brush unit12. Additionally, in the cleaning/drying unit 13, a pure water issupplied to rinse the wafer 21 while the wafer 21 is being rotated, anda drying is performed by high-speed rotation.

Here, a cleaning method using the cleaning system constituted as abovewill be described.

First, the wafer 21 on which the CMP processing is completed is conveyedto the first brush unit 11, and the wafer 21 is held by the rollers 4.Next, the wafer 21 is rotated by rotating the rollers 4. Rotation speedat this time is not specifically limited, but is 50 rotations perminute, for example. Next, while the front surface cleaning brush 3 aand the rear surface cleaning brush 3 b are being rotated, they are madeto contact both surfaces of the wafer 21. Rotation speed at this time isnot specifically limited, but is 200 rotations per minute, for example.

Incidentally, it is preferable that the pure water is supplied to thewafer 21 from the pure water nozzles 5 a and 5 b during the period froma holding of the wafer 21 by the rollers 4 to startings of the rotationof the wafer 21 and the rotation of the brush 3 so that the wafer 21does not become dry.

After the front surface cleaning brush 3 a and the rear surface cleaningbrush 3 b are made to contact the wafer 21, the both end portions of thefront surface cleaning brush 3 a and the rear surface cleaning brush 3 bare deformed by means of pressurizing the both ends of the front surfacecleaning brush 3 a and the rear surface cleaning brush 3 b by thepressure portions 1. That is, the both end portions of the front surfacecleaning brush 3 a and the rear surface cleaning brush 3 b arecompressed so that the diameters in the both end portions are enlargedas shown in FIG. 4. As a consequence, the entire front surface of thewafer 21 is made to contact the front surface cleaning brush 3 asubstantially evenly, even if the wafer 21 is warped into a shape of amound. Therefore, a cleaning efficiency of the outer peripheral portionof the wafer 21 improves. Incidentally, a magnitude of the pressureapplied by the pressure portions 1 is not specifically limited, but isabout 0.1 kgw/cm², for example.

While the front surface cleaning brush 3 a and the rear surface cleaningbrush 3 b are being rotated in contact with the wafer 21, an alkalinechemical solution is supplied to the wafer 21 from the chemical nozzles6 a and 6 b. A composition of the alkaline chemical solution is notspecifically limited, but an ammonia solution of about 0.5 weightpercent, for example, is used. Also, supplying time is not specificallylimited, but is about 30 seconds, for example.

The foreign objects such as abrasive grain on the front surface and therear surface of the wafer 21 are removed by means of such rotation,pressurizing, and supplying of the chemical solution.

After a brush cleaning is performed for a predetermined time, the frontsurface cleaning brush 3 a and the rear surface cleaning brush 3 b areseparated from the wafer 21 and the rotation is halted. Then, the purewater is supplied to the wafer 21 from the pure water nozzles 5 a and 5b to rinse the front surface and the rear surface of the wafer 21.

Subsequently, the wafer 21 is conveyed to the second brush unit 12 andthe wafer 21 is held by the rollers 4. Next, the wafer 21 is rotated byrotating the rollers 4. Rotation speed at this time is not specificallylimited, but is 50 rotations per minute, for example.

Next, an acid chemical solution is supplied to the wafer 21 from thechemical nozzles 6 a and 6 b. A composition of the acid chemicalsolution is not specifically limited, but a hydrofluoric acid of about0.5 weight percent, for example, is used. Also, supplying time is notspecifically limited, but is about 10 seconds, for example.

Incidentally, during the cleaning using the acid chemical solution, thefront surface cleaning brush 3 a and the rear surface cleaning brush 3 bmay be made to contact the both surfaces of the wafer 21 while beingrotated, similarly to the brush cleaning in the first brush unit 11.Rotation speed at this time is not specifically limited, but is 200rotations per minute, for example. It is preferable that the pure wateris supplied to the wafer 21 from the pure water nozzles 5 a and 5 bduring the period from a holding of the wafer 21 by the rollers 4 tostartings of the rotation of the wafer 21 and the rotation of the brush3 so that the wafer 21 does not become dry.

Further, after the front surface cleaning brush 3 a and the rear surfacecleaning brush 3 b are made to contact the wafer 21, the both endportions of the front surface cleaning brush 3 a and the rear surfacecleaning brush 3 b are deformed by means of pressurizing the both endsof the front surface cleaning brush 3 a and the rear surface cleaningbrush 3 b by the pressure portions 1, similarly to the brush cleaning inthe first brush unit 11. That is, the both end portions of the frontsurface cleaning brush 3 a and the rear surface cleaning brush 3 b arecompressed so that the diameters in the both end portions are enlargedas shown in FIG. 4. Incidentally, a magnitude of the pressure applied bythe pressure portions 1 is not specifically limited, but is about 0.1kgw/cm², for example. The pressurizing may be started during the periodin which the front surface cleaning brush 3 a and the rear surfacecleaning brush 3 b are being moved to contact the wafer 21. That is,timing to start the pressurizing is not limited to after the frontsurface cleaning brush 3 a and the rear surface cleaning brush 3 b aremade to contact the wafer 21.

After the cleaning for a predetermined time using the acid chemicalsolution, supplying of the acid from the nozzles 6 a and 6 b is stopped.Then, the pure water is supplied to the wafer 21 from the pure waternozzles 5 a and 5 b, to rinse the front surface and the rear surface ofthe wafer 21.

Subsequently, the wafer 21 is conveyed to the cleaning/drying unit 13and the wafer 21 is mounted on a rotatable stage. Then, the wafer 21 isrinsed with a pure water while being rotated at high speed.Subsequently, the wafer 21 is dried.

According to such a cleaning method using the cleaning apparatusaccording to the first embodiment, at the time of the brush cleaning,the front surface cleaning brush 3 a and the rear surface cleaning brush3 b are compressed and deformed to become easy to contact the outerperipheral portion of the wafer 21. Therefore, a high cleaningefficiency is achieved. Additionally, since conventional brushes can beused as the front surface cleaning brush 3 a and the rear surfacecleaning brush 3 b, a cost increase can also be suppressed.

Here, results of an observation actually carried out by the presentinventor will be described. In this observation, an oxide film of 500 nmin thickness is formed on a silicon wafer. Then, the oxide film ispolished to be 250 nm by a CMP processing and a foreign object (defect)on a wafer surface is measured using a wafer surface examining apparatus(LS6800 of Hitachi High-Technologies Corporation). The result of a casein which both end portions of the front surface cleaning brush 3 a andthe rear surface cleaning brush 3 b are pressurized is shown in FIG. 5while the result of a case in which the both end portions are notpressurized is shown in FIG. 6.

As shown in FIG. 6, when the both end portions of the front surfacecleaning brush 3 a and the rear surface cleaning brush 3 b are notpressurized, numerous foreign objects 22 exist in the outer peripheralportion of the wafer 21. On the other hand, as shown in FIG. 5, when theboth end portions of the front surface cleaning brush 3 a and the rearsurface cleaning brush 3 b are pressurized, the foreign objects 22scarcely exist over the entire surface of the wafer 21.

Incidentally, the pressures applied on the front surface cleaning brush3 a and the rear surface cleaning brush 3 b by the pressure portions 1may be differentiated from each other. For example, as shown in FIG. 4,when the wafer 21 is warped into the shape of the mound, the pressureapplied on the rear surface cleaning brush 3 b may be smaller than thepressure applied on the front surface cleaning brush 3 a, or only thefront surface cleaning brush 3 a may be compressed. In contrast, whenthe wafer 21 is warped into a shape of a bowl, the pressure applied onthe front surface cleaning brush 3 a may be smaller than the pressureapplied on the rear surface cleaning brush 3 b, or only the rear surfacecleaning brush 3 b may be compressed.

Second Embodiment

Next, a second embodiment of the present invention will be described.FIG. 7 is a front view showing a cleaning apparatus for a waferaccording to the second embodiment of the present invention.

In the second embodiment, a front surface cleaning brush 13 a isconstituted with three front surface cleaning brush pieces 13 a-1, 13a-2 and 13 a-3 as shown in FIG. 7. Also, a rear surface cleaning brush13 b is constituted with three rear surface cleaning brush pieces 13b-1, 13 b-2 and 13 b-3. These brush pieces are made of synthetic resinsuch as PVA (Poly Vinyl Alcohol), for example, on surfaces of which aplurality of projections are formed. One shaft 12 is inserted to thethree front surface cleaning brush pieces 13 a-1, 13 a-2 and 13 a-3,while one shaft 12 is inserted to the three rear surface cleaning brushpieces 13 b-1, 13 b-2 and 13 b-3. Cut-outs 14 are formed on twolocations of the shaft 12 as shown in FIG. 8A and FIG. 8B. To thecut-outs 14, disk-shaped stoppers 11 are fixed. A diameter of thestopper 11 is, for example, larger than a diameter of the shaft 12 byabout 5 mm to 10 mm.

The other constitution is the same as that of the first embodiment.

In the second embodiment as above, when both ends of the front surfacecleaning brush 13 a and the rear surface cleaning brush 13 b arepressurized by the pressure portions 1, as shown in FIG. 9, only thefront surface cleaning brush pieces 13 a-1 and 13 a-3 and the rearsurface cleaning brush pieces 13 b-1 and 13 b-3, which are located onthe both ends, are compressed, and the diameters thereof become large.As a consequence, the entire front surface of the wafer 21 is made tocontact the front surface cleaning brush 13 a substantially evenly, evenif the wafer 21 is warped into a shape of a mound. Therefore, a cleaningefficiency of the outer peripheral portion of the wafer 21 improves.Additionally, compared with the first embodiment, the cleaningefficiency is higher since deformations concentrate in the portionscontacting the outer peripheral portion of the wafer 21.

In the second embodiment, if the brush piece is required to beexchanged, it is only necessary to detach the stopper 11. Therefore, itis possible to easily cope with various kinds of warp directions andwarp amounts of the wafer by using a conventional brush whose diameteris uniform in a longitudinal direction as the brush piece and combiningthem.

Incidentally, in the first and the second embodiments, the constitutionin which the cleaning is performed with the wafer 21 being kepthorizontal is adopted, but a constitution in which the cleaning isperformed with the wafer 21 being kept vertical may be adopted. Also, anultra sonic cleaning unit may be provided in a prior step of a brushing,or in the cleaning/drying unit.

According to the present invention, since the diameters of the both endportions of the front surface cleaning brush is enlarged by theapplication of the pressure, the front surface cleaning brush can bemade evenly contact the entire front surface of the wafer even if thewafer is warped. Consequently, a high cleaning efficiency can beachieved even without using various kinds of brushes, so that cleaningof various wafers can be performed reliably.

The present embodiments are to be considered in all respects asillustrative and no restrictive, and all changes which come within themeaning and range of equivalency of the claims are therefore intended tobe embraced therein. The invention may be embodied in other specificforms without departing from the spirit or essential characteristicsthereof.

What is claimed is:
 1. A cleaning method for a wafer, comprising:contacting a front surface of the wafer with a straight-shaped frontsurface cleaning brush, the front surface cleaning brush rotating with afirst shaft being an axis, and contacting a rear surface of the waferwith a straight-shaped rear surface cleaning brush, the rear surfacecleaning brush rotating with a second shaft being an axis; and applyinga first pressure on the front surface cleaning brush from both ends toenlarge the diameters in both end portions of the front surface cleaningbrush, and applying a second pressure on the rear surface cleaning brushfrom both ends to enlarge the diameters in both end portions of the rearsurface cleaning brush, the first pressure applied on the front surfacecleaning brush being a pressure applied parallel to the first shaft, andthe second pressure applied on the rear surface cleaning brush being apressure applied parallel to the second shaft, wherein an inner surfaceof the front surface cleaning brush is directly in contact with asurface of the first shaft, wherein the front surface cleaning brush iscomposed of at least one single structure made of synthetic resin in aradial direction, wherein the first pressure applied on the frontsurface cleaning brush and the second pressure applied on the rearsurface cleaning brush are adjusted based on a direction of a warp ofthe wafer, wherein the second pressure applied on the rear surfacecleaning brush is smaller than the first pressure applied on the frontsurface cleaning brush in a case where the wafer is warped as convexedtoward the front surface side, and wherein the first pressure applied onthe front surface cleaning brush is smaller than the second pressureapplied on the rear surface cleaning brush in a case where the wafer iswarped as convexed toward the rear surface side.
 2. The cleaning methodfor the wafer according to claim 1, wherein the front surface cleaningbrush is constituted by combining three or more front surface cleaningbrush pieces disposed on a line, each of the front surface cleaningbrush pieces being composed of a single structure made of said syntheticresin in the radial direction.
 3. The cleaning method for the waferaccording to claim 1, wherein a brush made of synthetic resin is used asthe rear surface cleaning brush.
 4. The cleaning method for the waferaccording to claim 1, wherein the rear surface cleaning brush isconstituted by combining three or more rear surface cleaning brushpieces disposed on a line.
 5. The cleaning method for the waferaccording to claim 1, further comprising supplying an alkaline chemicalsolution to the front surface of the wafer.
 6. A manufacturing methodfor a semiconductor device, comprising: contacting a front surface ofthe wafer with a straight-shaped front surface cleaning brush, the frontsurface cleaning brush rotating with a first shaft being an axis, andcontacting a rear surface of the wafer with a straight-shaped rearsurface cleaning brush, the rear surface cleaning brush rotating with asecond shaft being an axis; and cleaning the wafer while applying afirst pressure on the front surface cleaning brush from both ends toenlarge the diameters in both end portions of the front surface cleaningbrush, and applying a second pressure on the rear surface cleaning brushfrom both ends to enlarge the diameters in both end portions of the rearsurface cleaning brush, the first pressure applied on the front surfacecleaning brush being a pressure applied parallel to the first shaft, andthe second pressure applied on the rear surface cleaning brush being apressure applied parallel to the second shaft, wherein an inner surfaceof the front surface cleaning brush is directly in contact with asurface of the first shaft, wherein the front surface cleaning brush iscomposed of a single structure made of synthetic resin, wherein thefirst pressure applied on the front surface cleaning brush and thesecond pressure applied on the rear surface cleaning brush are adjustedbased on a direction of a warp of the wafer, wherein the second pressureapplied on the rear surface cleaning brush is smaller than the firstpressure applied on the front surface cleaning brush in a case where thewafer is warped as convexed toward the front surface side, and whereinthe first pressure applied on the front surface cleaning brush issmaller than the second pressure applied on the rear surface cleaningbrush in a case where the wafer is warped as convexed toward the rearsurface side.
 7. A manufacturing method for a semiconductor device,comprising: contacting a front surface of the wafer with astraight-shaped front surface cleaning brush, and contacting a rearsurface of the wafer with a straight-shaped rear surface cleaning brush;and cleaning the wafer while applying a first pressure on the frontsurface cleaning brush from both ends to enlarge the diameters in bothend portions of the front surface cleaning brush, and applying a secondpressure on the rear surface cleaning brush from both ends to enlargethe diameters in both end portions of the rear surface cleaning brush,the first pressure applied on the front surface cleaning brush being apressure applied parallel to a first shaft of the front surface cleaningbrush, and the second pressure applied on the rear surface cleaningbrush being a pressure applied parallel to a second shaft of the rearsurface cleaning brush, wherein the first pressure applied on the frontsurface cleaning brush and the second pressure applied on the rearsurface cleaning brush are adjusted based on a direction of a warp ofthe wafer, wherein the second pressure applied on the rear surfacecleaning brush is smaller than the first pressure applied on the frontsurface cleaning brush in a case where the wafer is warped as convexedtoward the front surface side, and wherein the first pressure applied onthe front surface cleaning brush is smaller than the second pressureapplied on the rear surface cleaning brush in a case where the wafer iswarped as convexed toward the rear surface side.